NCDC Releases August 2012 U.S. Monthly Climate Report

According to NOAA scientists, the average temperature for the contiguous United States during August was 74.4°F, 1.6°F above the long-term average, marking the 16th warmest August on record. The warmer than average August, in combination with the hottest July and a warmer than average June, contributed to the third hottest summer on record since recordkeeping began in 1895.

Higher-than-average temperatures occurred across much of the West. Nevada tied August 1934 as its warmest August on record, with a statewide temperature 4.0°F above average. Six additional states across the region had August temperatures ranking among their ten warmest. Much of the Northeast was also warmer than average, where five states from Maine to Delaware had monthly temperatures among their ten warmest.

Drier-than-average conditions stretched from the Pacific Northwest, through the Rockies, and into the Upper Midwest. Nebraska, Washington, and Wyoming each had their driest August on record. Colorado, Idaho, and Oregon each had a top ten dry August.

Hurricane Isaac made landfall along Louisiana’s coast on August 28 with maximum sustained winds of 80 mph. The major impacts from the hurricane were storm surge along the Gulf Coast and heavy rainfall, both of which were driven partially by the storm’s slow motion and large size. Isaac contributed to Louisiana and Mississippi’s second wettest August on record, as well as Florida’s fourth wettest and Alabama’s eighth wettest. The storm also provided some relief to drought-stricken areas of the Midwest.

According to the U.S. Drought Monitor update on August 28, 2012 (the day Hurricane Isaac made landfall), 62.9 percent of the contiguous U.S. was experiencing moderate-to-exceptional drought, the same as the end of July. The percent area of the Nation experiencing the worst drought category, exceptional drought, doubled from 3 percent of the contiguous United States at the end of July to 6 percent at the end of August.

According to the Palmer Drought Index, which goes back to the beginning of the 20th century, 55.1 percent of the contiguous United States was in moderate to extreme drought in August, a decrease of about 3 percent compared to the previous month. The percent of the country in severe to extreme drought increased to 39.0 percent, indicating that the drought has intensified. The 2012 values have been exceeded only by the droughts of the 1930s and 1950s.

This monthly analysis (summary, full report) from NOAA's National Climatic Data Center is part of the suite of climate services NOAA provides government, business, and community leaders so they can make informed decisions.